What do British Royal family, the Town of Bent Necks, Adidas & Puma, the Mangeshkar sisters and Britpop band Oasis have in common?

Sibling love may be one of the purest and longest-lasting bonds we know—but where there is love, there can also be rivalry. From childhood one-upmanship and bruised egos to battles over money, power and success, sibling relationships can take surprisingly complicated turns.